t0052: add simple-ipc tests and t/helper/test-simple-ipc tool

Create t0052-simple-ipc.sh with unit tests for the "simple-ipc" mechanism.

Create t/helper/test-simple-ipc test tool to exercise the "simple-ipc"
functions.

When the tool is invoked with "run-daemon", it runs a server to listen
for "simple-ipc" connections on a test socket or named pipe and
responds to a set of commands to exercise/stress the communication
setup.

When the tool is invoked with "start-daemon", it spawns a "run-daemon"
command in the background and waits for the server to become ready
before exiting.  (This helps make unit tests in t0052 more predictable
and avoids the need for arbitrary sleeps in the test script.)

The tool also has a series of client "send" commands to send commands
and data to a server instance.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 122 insertions, 0 deletions

diff --git a/t/t0052-simple-ipc.sh b/t/t0052-simple-ipc.sh
new file mode 100755
index 0000000000..ff98be31a5
--- /dev/null
+++ b/t/t0052-simple-ipc.sh
@@ -0,0 +1,122 @@
+#!/bin/sh
+
+test_description='simple command server'
+
+. ./test-lib.sh
+
+test-tool simple-ipc SUPPORTS_SIMPLE_IPC || {
+	skip_all='simple IPC not supported on this platform'
+	test_done
+}
+
+stop_simple_IPC_server () {
+	test-tool simple-ipc stop-daemon
+}
+
+test_expect_success 'start simple command server' '
+	test_atexit stop_simple_IPC_server &&
+	test-tool simple-ipc start-daemon --threads=8 &&
+	test-tool simple-ipc is-active
+'
+
+test_expect_success 'simple command server' '
+	test-tool simple-ipc send --token=ping >actual &&
+	echo pong >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'servers cannot share the same path' '
+	test_must_fail test-tool simple-ipc run-daemon &&
+	test-tool simple-ipc is-active
+'
+
+test_expect_success 'big response' '
+	test-tool simple-ipc send --token=big >actual &&
+	test_line_count -ge 10000 actual &&
+	grep -q "big: [0]*9999\$" actual
+'
+
+test_expect_success 'chunk response' '
+	test-tool simple-ipc send --token=chunk >actual &&
+	test_line_count -ge 10000 actual &&
+	grep -q "big: [0]*9999\$" actual
+'
+
+test_expect_success 'slow response' '
+	test-tool simple-ipc send --token=slow >actual &&
+	test_line_count -ge 100 actual &&
+	grep -q "big: [0]*99\$" actual
+'
+
+# Send an IPC with n=100,000 bytes of ballast.  This should be large enough
+# to force both the kernel and the pkt-line layer to chunk the message to the
+# daemon and for the daemon to receive it in chunks.
+#
+test_expect_success 'sendbytes' '
+	test-tool simple-ipc sendbytes --bytecount=100000 --byte=A >actual &&
+	grep "sent:A00100000 rcvd:A00100000" actual
+'
+
+# Start a series of <threads> client threads that each make <batchsize>
+# IPC requests to the server.  Each (<threads> * <batchsize>) request
+# will open a new connection to the server and randomly bind to a server
+# thread.  Each client thread exits after completing its batch.  So the
+# total number of live client threads will be smaller than the total.
+# Each request will send a message containing at least <bytecount> bytes
+# of ballast.  (Responses are small.)
+#
+# The purpose here is to test threading in the server and responding to
+# many concurrent client requests (regardless of whether they come from
+# 1 client process or many).  And to test that the server side of the
+# named pipe/socket is stable.  (On Windows this means that the server
+# pipe is properly recycled.)
+#
+# On Windows it also lets us adjust the connection timeout in the
+# `ipc_client_send_command()`.
+#
+# Note it is easy to drive the system into failure by requesting an
+# insane number of threads on client or server and/or increasing the
+# per-thread batchsize or the per-request bytecount (ballast).
+# On Windows these failures look like "pipe is busy" errors.
+# So I've chosen fairly conservative values for now.
+#
+# We expect output of the form "sent:<letter><length> ..."
+# With terms (7, 19, 13) we expect:
+#   <letter> in [A-G]
+#   <length> in [19+0 .. 19+(13-1)]
+# and (7 * 13) successful responses.
+#
+test_expect_success 'stress test threads' '
+	test-tool simple-ipc multiple \
+		--threads=7 \
+		--bytecount=19 \
+		--batchsize=13 \
+		>actual &&
+	test_line_count = 92 actual &&
+	grep "good 91" actual &&
+	grep "sent:A" <actual >actual_a &&
+	cat >expect_a <<-EOF &&
+		sent:A00000019 rcvd:A00000019
+		sent:A00000020 rcvd:A00000020
+		sent:A00000021 rcvd:A00000021
+		sent:A00000022 rcvd:A00000022
+		sent:A00000023 rcvd:A00000023
+		sent:A00000024 rcvd:A00000024
+		sent:A00000025 rcvd:A00000025
+		sent:A00000026 rcvd:A00000026
+		sent:A00000027 rcvd:A00000027
+		sent:A00000028 rcvd:A00000028
+		sent:A00000029 rcvd:A00000029
+		sent:A00000030 rcvd:A00000030
+		sent:A00000031 rcvd:A00000031
+	EOF
+	test_cmp expect_a actual_a
+'
+
+test_expect_success 'stop-daemon works' '
+	test-tool simple-ipc stop-daemon &&
+	test_must_fail test-tool simple-ipc is-active &&
+	test_must_fail test-tool simple-ipc send --token=ping
+'
+
+test_done